Fluids like liquids or gases have to be transported via flow channels in numerous technical applications. Flow channels often contain branches, which have a flow direction substantially perpendicular to the flow direction of a main flow channel, for a flow separation where cross flows are used. At such branch turbulences usually develop at the edges of the inlet and cause unwanted pressure losses. One method to reduce the turbulences is the chamfering of the edges of the inlet.
EP 0 365 195 A2 shows a variety of configurations for convergent-divergent film cooling holes with frusto-conical portions connected at their narrowest parts, together with the hole drilling methods necessary to achieve the configurations.
EP 1 686 240 A1 shows cooling holes where the regions of a pointed edge are broken along the periphery, so that a flat portion is made available in the region.
Hot gas path components are one application for cross flows. These components are exposed to high temperatures and have to be cooled. Especially the hot gas components of a gas turbine, like turbine blades or vanes, are often continuously cooled, where film and impingement cooling plays a considerable role. For film cooling the component has to be hollow and holes connect the inside with the outside of the component. This provides that the cooling flow from the inside enters the holes and generates a thin cooling film also at the outside of the blade. The here applied cross flow through the holes is subjected to the already mentioned unwanted pressure losses, which may reduce the effectiveness of the film cooling. The same is valid for the impingement cooling, where the flow is blown out through holes in a wall of a flow channel so as to impinge on the back side of the wall to be cooled.